inet: fix race in reqsk_queue_unlink()
reqsk_timer_handler() tests if icsk_accept_queue.listen_opt
is NULL at its beginning.
By the time it calls inet_csk_reqsk_queue_drop() and
reqsk_queue_unlink(), listener might have been closed and
inet_csk_listen_stop() had called reqsk_queue_yank_acceptq()
which sets icsk_accept_queue.listen_opt to NULL
We therefore need to correctly check listen_opt being NULL
after holding syn_wait_lock for proper synchronization.
Fixes: fa76ce7328b2 ("inet: get rid of central tcp/dccp listener timer")
Fixes: b357a364c57c ("inet: fix possible panic in reqsk_queue_unlink()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 7bb9c39..61b45a1 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -577,21 +577,22 @@
static bool reqsk_queue_unlink(struct request_sock_queue *queue,
struct request_sock *req)
{
- struct listen_sock *lopt = queue->listen_opt;
struct request_sock **prev;
+ struct listen_sock *lopt;
bool found = false;
spin_lock(&queue->syn_wait_lock);
-
- for (prev = &lopt->syn_table[req->rsk_hash]; *prev != NULL;
- prev = &(*prev)->dl_next) {
- if (*prev == req) {
- *prev = req->dl_next;
- found = true;
- break;
+ lopt = queue->listen_opt;
+ if (lopt) {
+ for (prev = &lopt->syn_table[req->rsk_hash]; *prev != NULL;
+ prev = &(*prev)->dl_next) {
+ if (*prev == req) {
+ *prev = req->dl_next;
+ found = true;
+ break;
+ }
}
}
-
spin_unlock(&queue->syn_wait_lock);
if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
reqsk_put(req);